Provided is a method for generating a feedback message for ARQ including recording an ACK type in a first field; estimating the last block sequence number of successively ACKed blocks and recording the estimated last block sequence number in a second field; recording the number of groups of successively ACKed blocks after the estimated last block sequence number as the number of ACK MAPs in a third field; recording the startblock sequence number of the respective ACK MAPs in a fourth field; recording the lengths of the respective ACK MAPs in a fifth field corresponding to the recorded start block sequence number; and sending a feedback message including information on the first to the fifth fields.